1. Field of the Invention
The present invention relates to a lithium-ion battery and a method for regenerating the same.
2. Background Art
In view of environmental protection and energy conservation, hybrid vehicles, in which engines and motors are used in combination as power sources, have been developed and commercialized. In addition, for the future, fuel cell hybrid vehicles, in which fuel cells are used instead of engines, are being actively developed.
For hybrid vehicles, the use of secondary batteries which can be electrically charged and discharged in a repetitive manner as power sources is essential technology. Among secondary batteries, in particular, lithium ion (secondary) batteries are characterized by high operating voltage and high energy density that facilitates achievement of high output. Therefore, lithium ion secondary batteries are increasingly growing in importance as power sources of hybrid vehicles for the future.
A technical object for lithium-ion batteries used as hybrid vehicle power sources is to prevent an increase in resistance during high temperature storage at 50° C. or more.
Hitherto, in order to prevent an increase in resistance during high temperature storage, the addition of a compound such as vinylene carbonate to an electrolyte has been suggested.
For example, Journal of The Electrochemical Society, 151 (10) A1659-A1669 (2004) suggests a battery which can be prevented from deteriorating during storage at 60° C. with the addition of vinylene carbonate (2 wt %) to an electrolyte comprising LiPF6, ethylene carbonate, and dimethyl carbonate that results in formation of a coating film on the surface of a negative electrode.